The invention relates to a device for reversal of direction of planar letters in letter sorting systems with cover band conveyors for introducing and removing letters.
In letter sorting systems in which planar letters are fed to units such as readers and printing equipment, in order to sort letters according to sorting information appended to their surface, this sorting information must be located at defined positions. If it is not, the letters must be brought into the working position by turning them around their longitudinal or vertical axis.
To this end a device for reversing the direction (the front edge becomes the rear edge after the re-insertion into the flow of letters) is known (DE 43 45 160 C2). A collision-free reversal of two letters following each other however requires the first letter to be reversed to have already left the device before the second letter enters it. With the usual high conveyance speeds this would lead to impermissibly large minimum gaps between consecutive letters. By using two reversing devices it is however possible to reverse even consecutive letters with small gaps. In this case the letters are fed alternately into one of the two reversing devices. In the device each letter to be reversed is stopped and travels backwards again out of the device.
Corresponding compact-design devices for reversing the direction of planar letters with two reversing devices are known from U.S. Pat. No. 6,550,621 B1.